The present invention relates to additives for water-based functional fluids.
Benzotriazole and derivatives thereof have been known for many years to be effective metal passivators, especially as copper passivators, for use in a range of substrates. Benzotriazole itself and many of its derivatives have, however, limited application because of their poor solubility.
British Pat. No. 1,061,904 describes benzotriazole derivatives with various non-polar substituents which are useful metal passivators for non-aqueous based systems such as oils, lubricants and some hydraulic fluids.
Certain previously unknown benzotriazole and benzimidazole derivatives having polar substituents combine an improved level of solubility in a wide range of water-based functional fluids along with a high level of metal passivation.
Accordingly, the present invention pertains to such derivatives and to compositions passivated thereby.